1. Field of Invention
The invention relates to the adhesion of elastomers to a brass plated reinforcing wire, wherein the elastomers contain a polysulfide as an adhesion promoter.
2. Prior Art Statement
It is well known in the art to reinforce rubber articles or products with metal elements such as steel wire. It is, of course, of the utmost importance that the bond between the rubber and the metal element should be as strong as possible and remain intact over a long period of time, even under severe conditions. One of the problems which has been recognized is that steel is very prone to oxidation, which even in minor degrees is highly deleterious to the rubber-metal bond. The corrosion problem generally has been eliminated by coating the steel wire with brass or other alloys.
Further improvement in the adhesion of rubber to coated wire, particularly brass plated steel wire, has been proposed. For example, U.S. Pat. No. 4,605,693 to Mowdood discloses rubber articles reinforced with brass plated steel wire elements, wherein the rubber article contains an adhesion promoter selected from the group consisting of allyl phosphate esters, allyl phosphite esters, 5-nitro isatoic anhydride, iminodiacetic acid, and salts thereof.
U.S. Pat. No. 3,897,583 to Bellamy discloses improved adhesion of rubber to metal wire, particularly, brass coated wire using a cobalt salt dispersed in the rubber.
U.S. Pat. No. 4,340,515 to Frassek et al. teaches a use of a solid rubber adhesion promoter composition comprising cobalt naphthenate, nickel naphthenate or a mixture thereof and cobalt resinate, nickel resinate or a mixture thereof to improve the adhesion of rubber to a brass plated wire.
U.S. Pat. No. 4,075,159 to Koyama et al. teaches the addition of benzoic acid or monohydroxybenzoic acid to rubber to improve the adhesion of rubber to brass plated reinforcing elements.
U.S. Pat. No. 3,112,772 to Connor et al. discloses the use of a lead salt such as lead acetate, lead subacetate or lead carbonate uniformly dispersed in a polychloroprene elastomer to increase bonding of the elastomer to metal reinforcing elements.
U.S. Pat. No. 4,851,469 to Saitoh discloses the use of a combination of silica, a resorcin donor, a methylene donor and an organic sulfur-containing compound to improve the adhesion of sulfur-vulcanizable rubber to brass.
U.S. Pat. No. 3,443,986 to Wanatabe et al. teaches a process for treating nylon or rayon fiber with a composition containing resorcinol, formolin, rubber latex and a wax to improve the adhesion of said fibers to rubber.
U.S. Pat. No. 3,480,508 to Roy teaches the improvement in adhesion of nylon cord to rubber in the manufacture of tires by inclusion of dibenzothiazyldisulfide, mercaptobenzothiazol, tetramethylthuiuram disulfide and a quinone dioxime in the rubber vulcanization recipe.
U.S. Pat. No. 4,752,507 to Johansson et al. teaches increasing the adhesion of rubber to a substrate by the addition of a vulcanizing agent consisting of sulfur and at least one unsaturated reactant such as d-limonene, 5-ethylidene-2-norbornene, styrene, or dicyclopentadiene.
U.S. Pat. No. 2,701,221 to Clayton, Jr. et al. teaches the use of tetramethylthiuram disulfide as an accelerator for a rubber cement in the bonding of low unsaturation rubber to natural rubber.
U.S. Pat. No. 4,405,758 to Jablonsky shows tetramethylthiuram disulfide or group IB, IIB, IVA, VA, or VIA salts thereof in combination with sodium stearate as being an effective accelerator for acrylate rubbers containing both carboxyl and active halogen groups.
In the present application, it has been found that certain of the polysulfides function as a retarder in the elastomers of the present invention.